Determination of ventilation rate of residential buildings through temperature measurement

Natural ventilation plays a very important role in improving indoor climate and reducing energy consumption of residential buildings. However, there is not enough data on real measurements of natural ventilation rate from buildings, especially from residential buildings. This is due to the complex flow field and the dynamic behavior of matural ventilation, which make it very difficult to carry out continual measurement of natural ventilation in the field. This research tries to get some knowledge of natural. ventilation in residential buildings through temperature measurement. Hourly room air temperature has been measured nearly one month during the summer of 1999 in 98 non-air conditioned flats in Beijing. Simulation has then been carried out on five of the measured flats for room air temperature based on the investigated indoor casual gains and the measured weather data. Difference between measured and simulated temperatures has been obtained. Ventilation rate is then introduced at each hour to minimize the gap. In this way, hourly ventilation rates during the measuring period can be identified for the measured rooms in the five flats. In addition to the consistency of simulated temperature with measured temperature, the range of identified ventilation rates covers well some natural ventilation measurements obtained by tracer gas technique. Moreover, questions have been asked to the occupants on when they open windows and when they close them. Results show that the variation of the identified ventilation rates is quite closed to the window operations reported by the occupants.